Large-pored water filter kills bacteria instantly

Engineers from Stanford University’s Department of Materials Science and Engineering have developed and tested an inexpensive new filtering technology that kills up to 98 per cent of disease-causing bacteria in water in seconds without clogging.

According to associate professor Yi Cui from Stanford’s Department of Materials Science and Engineering, most water purifiers work by trapping bacteria in tiny pores of filter material. But pushing water through those filters requires electric pumps and consumes a lot of energy. Furthermore, the filters can get clogged and must be changed periodically.

The new material, in contrast, has relatively large pores, which allow water to flow through them easily. And it kills bacteria outright, rather than just trapping them.

To create the material for the filter, the researchers spread sub-microscopic silver nanowires onto cotton, and then added a coating of carbon nanotubes to form a complex, electrically conducting, high-surface-area coating that could kill water-borne bacteria.

Tests of the material on E. coli-tainted water showed that the silver/electrified cotton killed up to 98 per cent of the bacteria. The filter material never clogged and the water flowed through it very quickly without any need for a pump.

The researchers believe that the technology could dramatically lower the cost of filtration technologies where the need to frequently replace filters is costly and difficult.

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